1. Field of the Invention
The present invention relates to a gas cooking appliance in which a thermal power control valve of a burner is driven by an electric motor such as a stepping motor.
2. Description of the Related Art
For this type of gas cooking appliance, those found in, for example, Japanese Patent Laid-Open No. 2000-179860 (patent document 1) and Japanese Patent Laid-Open No. 2003-130333 (patent document 2) have been known. In the gas cooking appliance found in patent documents 1 and 2, a thermal power control valve of a burner is driven by a stepping motor.
In the gas cooking appliance found in patent document 1, as shown in FIG. 17 of the document, the thermal power control valve is displaced to a closed position by the stepping motor when the burner is extinguished, and the thermal power control valve is displaced by the stepping motor to a middle/high position which is a displacement position for ignition of the burner when an instruction to ignite the burner is provided. In the gas cooking appliance found in patent document 2, as shown in FIG. 5 of the document, the thermal power control valve is displaced to a home position (closed position) by the stepping motor, and then the thermal power control valve is displaced to a middle fire position which is a displacement position of the thermal power control valve for ignition of the burner when an ignition instruction is provided.
In techniques found in the patent documents 1, 2, the thermal power control valve is displaced from a position on the closed side to a position for ignition when the burner is ignited as described above. Hence, there is a disadvantage that when a user of the gas cooking appliance performs an ignition instruction operation, an ignition process of the burner (supply of gas to the burner and actuation of an ignition device) is not started until the thermal power control valve is displaced to the position for ignition, thus causing a time delay before an actual ignition process of the burner is started for the ignition instruction operation by the user. In particular, for the gas cooking appliance comprising a plurality of stepping motors wherein the stepping motors are not concurrently actuated, but actuated one after another according to a predetermined order of priority as in the technique found in patent document 1, the start of the ignition process of burners of lower priority orders is considerably delayed when ignition instruction operations are almost concurrently performed for a plurality of burners.
The present invention has been made in view of the background described above, and its object is to provide a gas cooking appliance comprising a thermal power control valve driven by an electric motor such as a stepping motor, wherein the delay of the start of the ignition process of the burner for an ignition request can be eliminated to start the ignition process promptly.